1. Field of the Invention
The present invention relates to a localized over-molding die structure, and more particularly, to a localized over-molding die structure, wherein it is possible to prevent from an existing circumstance (hereinafter, it is referred to an ‘overflow’) that an injection resin flows over at the material boundary when a localized over-molding process proceeds
2. Description of Prior Art
In general, a localized over-molding means a mold for embodying the tone of color, the quality of the material, the sense of touch or the like, by injecting each of two materials in only a mold in a localized area.
When the localized over-molding is performed, the width of the second injection part and the position of a gate may be various with every production, and accordingly, a pressure on the material boundary may be different.
Commonly, when the width of the second injection part becomes large, the pressure for filling up all of the width becomes large, and a deviation of the pressure according to the position of the material boundary becomes large as well.
In order to overcome a problem that an overflow occurs in the material boundary with an excessive pressure, a simple groove was formed in the prior art, but, in case of this, when the width of the second injection part becomes large, the overflow occurred still, and there was a limit to improve the injection pressure for the second molding.
That is, since there was a limit to improve the injection pressure in a prior section of the material boundary, there are restricted in the width and the thickness of the second injection part, and accordingly, there was a problem that a degree of freedom in a design becomes worse.
FIGS. 1A to 1D are section-views showing an over-molding process in the conventional localized over-molding die structure, respectively, and more particularly, section-views showing an over-molding process for a large sized component.
As shown in FIGS. 1A to 1D, the localized over-molding die structure according to the prior art includes, a core die 10 arranged in a lower side; a cavity die 30 arranged in a upper side; and a slide die 50 for moving upward and downward at in the inner space 35 of the cavity die 30, wherein, the first gate 100 and the second gate 200 are arranged in the side part of the cavity die 30 in order to inject an injection resin into the inside part of the cavity die 30, respectively.
In the localized over-molding die structure, by lifting forcibly up the slide die 50 after the first injection is performed, the slide die 50 may play a role in securing a defined space on the upper side of the first injection material 110 so that the second injection is performed.
Now, a localized over-molding process will be explained referring to FIGS. 1A to 1D.
First, by injecting a resin through the first gate 100, the first injection material 110 is formed (referring to FIG. 1A). Next, by lifting up the slide die 50, an inner space is formed on the upper side of the first injection material 110 (referring to FIG. 1B), and then, by injecting other resin through the second gate 200, the second injection material 210 is formed on the upper side of the first injection material 110 (referring to FIG. 1C).
Here, in the boundary between two materials on which both of the first injection material 110 and the second injection material 210 are formed, it was known that the overflow resin 230 may remain (referring to FIG. 1D).
On the other hand, FIG. 2 is a view illustrating a practical aspect which an overflow is formed in a process of the conventional localized over-molding.
As shown in FIG. 2, it was known that an overflow resin 230 is protruded through a gap in the boundary between two materials.
FIG. 3 is an enlarged view for enlarging “A” part of FIG. 1D for explaining a cause which an overflow occurs in the conventional localized over-molding die structure.
In the localized over-molding die structure, there are some reasons why the overflow is formed, as follows.
Firstly, by means of the second injection pressure (a process of FIG. 1C) which is applied during a process before the first injection material 110 is completely cooled, the first injection material 110 is shoved, and accordingly, a gap between the first injection material 110 and the slide die 50 is formed (in case of (a) in FIG. 3).
Secondly, the cavity die 30 may be shoved by forming a gap between the cavity die 30 and the slide die 50, and a gap may be generated by heat distortion of the mold. Besides, by setting an incline (of about 1 degree) between the side mold 50 and the first injection material 110, a gap at the junction part may be formed (in case of (b) in FIG. 3).
According to the localized over-molding die structure of the prior art, the overflow may inevitably occur at the localized boundary of two materials by the above-described reasons, and accordingly, the problems may occur that a yield of the products in the manufacturing process is depreciated and the quality of the vehicle appearance is deteriorated.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.